File Work: E1207y Pac

function FindProxyForURL(url, host) 
    if (shExpMatch(host, "*.internal.local")) return "DIRECT";
    if (url.substring(0, 6) === "https:") return "PROXY secure-proxy.corp.com:8080";
    return "PROXY proxy.corp.com:3128";

A PAC file tells your browser or operating system:

The e1207y version is typically found in: e1207y pac file work

Older versions of e1207y contain a fatal flaw: they use dnsResolve(host) for every request. If your corporate DNS is slow (over 50ms), the browser hangs. Fix: Replace dnsResolve() with isInNet() if possible, or reduce reliance on live DNS calls. A PAC file tells your browser or operating system:

var clientIP = myIpAddress();
if (isInNet(clientIP, "192.168.1.0", "255.255.255.0")) 
    return "PROXY high-bandwidth-proxy:8080";
 else 
    return "PROXY low-bandwidth-proxy:8080";